A crew member on a tourist boat has been stung by a cone snail on Whitsunday Island off north Queensland, causing his respiratory system to start shutting down.

The 25-year-old was walking barefoot in shallow water near Whitehaven Beach when the cone snail's harpoon pierced his skin about midday on Tuesday.

Considering the incoming tide, there was only a small window for the man to be flown to hospital, RACQ CQ Rescue crewman Ethan Clissold said.

The pilot managed to land on a narrow patch of sand at Tongue Bay and the patient was brought to the helicopter by an inflatable boat.

"If we had any delays in getting him on the helicopter so the medical team could stabilise and administer pain relief, we would have needed to rethink our landing strategy, wasting precious time in the process," Mr Clissold said.

The man was taken to the Mackay Base Hospital where he remains in a stable condition.

What is a cone snail?

A cone snail has a cone-shaped shell, a head and tentacles

They are typically found in warm tropical seas

There are over 800 different species

Cone snails are carnivorous and predatory, using a venomous "harpoon" to sting prey